Chester e



UNITED sTATns P ENT onmon.

CHESTER n. ANDREWS, or PITTSBURGH, PENNSYLVANI As'SIeNon. To Tnn'snLnnNCOMPANY, or PITTSBURGH, PENNSYLVANIA, A conPonATIoN or DELAWARE.

' Pnocnss or oxmA IoN or AnoiuATIo BODIES.

No Drawing.

To all whom it may concern: Be it known that I, CHESTER E. ANDREWS, acitizen of the United States, residing at Pittsburgh, Pennsylvania, haveinvented certain new and useful Improvements in Processes of Oxidationof Aromatic Bodies, of which the following is a specification.

The present invention relates to the oxidation of aromatic hydrocarbonscontaining either one or more side, chains or consisting of a pluralityof rings by the use of sulfuric acid with or Without an additionaloxidizing agent and with the intervention of a suitable catalyst, thelatter consisting essentially of an oxid or another compound of eitherof the metals, molybdenum or vanadium. As examples of the hydrocarbonsto be used xylene, toluene, naphthalene and anthracene are cited Theinvention will be described in connection with the oxidation ofanthracene with the production of anthraquinone.

In the preferred form of operation the anthracene is boiled withsulfuric acid containing an oxidizing agent such as sodium dichromate,chromic acid, manganese dioxid, or others, together with the catalystwhich may preferably initially consist-of vanadium oxid V 0 The sulfuricacid may vary in strength within wide limits but 50% is preferred. Inthis way the reaction takes place with the formation of anthraquinone.

The reaction products may then be separated by diluting and cooling themixture and filtering off the crystals of anthraquinone. Theanthraquinone may be purified by any suitable means such as sublimation.In place of pure anthracene, mixtures containing this can be used. Theimpurities seem to be completely oxidized glving a product which isessentially anthraquinone.

In some cases, instead of employing a single catalyst it is advisable toemploy a mixture of the oxids or other compounds of the metals abovementioned. Also mixtures of either molybdenum or vanadium oxid with theoxid or other compound of one or more of the metals of the fifth orsixth groups of the periodic classification in many instances seem toact more efliciently as catalysts, than either the molybdenum or vana-Specification of Letters Patent.

Patented Dec. 9,1919.

Application filed May 25, 1918. Serial No. 236,552.

dium compounds alone. The catalyst may be m a state of coarse or'finedivision but preferably fine.

The strength of the sulfuric acid necessary varles considerably with thedifferent hydrocarbons. In the case of naphthalene concentrated sulfuricacid or oleum is to be used and the oxidizing agent omitted, thecatalyst alone being suflicient.

IVhenorthmxylene is employed as the starting material and sulfuric acidof about 50% used, with the catalysts above referred to, phthalicanhydrid can beproduced.

In all of the examples the operation is carried out by boiling themixtures, and the strength of the acid will of course determine thetemperature.

In all the examples, the amount of the catalyst employed materiallyaffects the speed of the reaction. The amount of the catalyst used maygenerally vary between the approximate limits of oneto five per cent.

The catalyst may be recovered for usegin thetreatment of a further batchof material if desired.

I am aware of the use of mercuric sulfateas a catalyst, for example, inthe oxidation of naphthalene to produce phthalic anhydrid. The oxids ofthe metals herein speci-' fied possess the great advantage over mercuricsulfate (or materials from which this IS derived) of being very muchmore *active and efficient so that even when adding one herein describedgroup comprising vanadium and molybdenum.

2. A process which comprises heating a mixture containin sulfuric acid,an oxi a'ble aromatic hy rocarbon and a catalyst comprising a vanadiumcompound.

3. A-process ofoxidation which comprises heating to about the boilingpoint, a mixture which comprises heating together a mixture containing apolyring aromatic hydrocarcomprising naphthalene and a concentrated bon,sulfuric acid and a catalyst comprising sulfuric acid, in the presenceof a vanadium 10 a compound of a metal of the herein deoxid as acatalyst. 5 scribed group consisting of vanadium and In testimonywhereof I have aifixed my molybdenum. signature.

4. A process of making phthalic anhydrid CHESTER E. ANDREWS.

